1. Field of the Invention
The invention relates to a measuring and testing system for a test piece having at least one operational fluid, particularly to test an internal combustion engine, with at least one measuring arrangement connected to a space of the test piece containing operational fluid, including a partial measuring arrangement for the quantity parameter of the operational fluid and at least one additional partial measuring arrangement for at least one quality parameter for the characterization of the physical and/or chemical condition of the operational fluid, as well as a control and evaluation unit connected to the measuring arrangement. The invention relates additionally to a measuring arrangement to determine at intervals the usability potential of at least one operational fluid used in an engine, to be used in the measuring and testing system having a connecting line to a space in the engine containing the operational fluid, a measuring vessel fillable with the operational fluid through a connecting line, an evaluation unit as well as a measuring and testing method for a test piece having at least one operational fluid, particularly to test an internal combustion engine, whereby there is determined a quantity parameter of the operational fluid and at least one condition parameter for the characterization of the physical and/or chemical condition of the operational fluid, and a method to determine at intervals the usability potential of at least one operational fluid employed in an engine to be used in such a measuring and testing method.
2. The Prior Art
Complex measuring and testing systems are required for research and development or for quality testing and diagnosis on complex engines, for example internal combustion engines, as well as reciprocating piston compressors, turbines, gearing and drive trains for vehicles, etc., which is to make thorough testing and optimizing of the machine possible. The operational fluids employed therein are of special significance in this connection, which are for example lubricating oil, cooling agents or possibly liquid, gaseous or powder-like motor fuels and combustion air. They have to be supplied to the engine in sufficient amounts and be of suitable condition and they are consumed during the operation of the engine. Consumption may occur in terms of quantity and/or condition whereby the cooling agent, for example, is normally not characterized by actual consumption in quantity but by the degree of flow capacity whereas the consumption during the combustion of motor fuel together with combustion air is practically complete in terms of quantity as well as in condition, while the consumption of lubricating oil occurs continuously with continuous deterioration in the way of a slow-moving alteration.
Measuring and testing systems are thereby often equipped with a number of corresponding measuring devices. They serve, on the one hand, to determine the quantity parameters of an operational fluid. Depending on the design and application, the actual intake flow, consumption flow, or flow-through can be determined as volume or mass per time unit, for example, or per operational cycle or accumulated value—or determined can be the quantity actually still remaining in the reservoir, or the difference in quantity or fluid level compared to the lastly measured value etc. On the other hand, measuring and testing systems are often equipped with measuring devices to determine the quantity parameters of the operational fluid, which make possible the characterization of the physical and/or chemical condition of the operational fluid. Such measuring devices and sensors to determine the condition parameters can also be installed into conditioning devices, for example, which serve for conditioning of temperature and pressure of the supplied motor fuel, or for conditioning of temperature, humidity and pressure of the supplied combustion air.
It is also basically known to mathematically link a quantity parameter to a condition parameter of the operational fluid and to determine in this way an additional, derived physical and chemical value of the operational fluid or an additional quantity or condition parameter. By multiplication of the quantity parameter of the “volume flow” with the condition parameter of the “density” one can often obtain the new quantity parameter of the “mass flow” for example. Or one can obtain the volume and the acoustic velocity of the flowing gas from the measured velocity of an ultrasound measuring system; and the actual gas density can be obtained from the acoustic velocity and the measured pressure as an additional condition parameter of the fluid so that the searched-for mass flow is obtained by multiplication of the volume flow and the density.
But in these cases, as in all known systems and devices, it is true that the quantity parameters and at least one condition parameter of the operational fluid are determined and evaluated separately and isolated, and whereby no information is given about the sensibility of a measurement under existing circumstances, about the validity of the determined values of quantity parameters, condition parameters and possibly other measuring and testing results.
Problems of special consideration relative to the quantity parameters appear particularly in the measurements of consumption of lubricating oils in modern internal combustion engines, which is of ever-increasing significance merely in view of the desired decrease in exhaust gas emission since lower oil consumption means a decrease of the amount of particles in case of a diesel engine and in view of an increase in service life of the exhaust gas treatment system.
For example, indicator methods are known in the measurement of oil consumption which determine the oil consumption in the exhaust gas through measurement of a component contained in the lubricating oil (e.g. radioactive substances, sulfur or the like) proportional to the consumption, which is above all expensive and relatively complicated in its application. In addition, there are devices and methods known with which oil consumption is determined with an oil level measurement directly in the crankcase sump of the internal combustion engine, for instance by means of suction systems based on a volumetric measurement. However, the measured values are negatively influenced by that change in oil density in this method and arrangement, which is cause by the change in oil temperature and foaming of the oil in the crankcase sump. In view of the low accuracy in measurement and the necessity to measure while the motor is turned off and the entire time needed to perform the measurement, there must be considered in its place a sensible application in production test benches, for example, to monitor the condition of the manufactured internal combustion engine. A part of these problems is avoided in known arrangements and methods of the aforementioned type by moving the oil level measurement to a communicating vessel outside of the internal combustion engine. With the aid of a predetermined calibration function, there can be determined the existing amount of lubricating oil or the amount of lubricating oil consumed between two measured values.
In arrangements of this type as disclosed, for example, in “SAE TECHNICAL PAPER SERIES 931667 E—Experience with Oil Consumption Measurements on the Engine Test Bed, Karl Köch, AVL List” or in DE 35 37 192 A1 or EP 0 416 267 A1, the connection of the measuring vessel to the internal combustion engine is made by means of an essentially horizontal connecting line starting from the oil plug disposed at the bottom of the oil pan of the internal combustion engine whereby the spaces above the lubricating oil of the internal combustion engine and the measuring vessel are connected to one another with a pressure compensation line.
In these methods and systems, which determine relatively rapidly, in general, low oil consumption values by means of a high discrimination in the oil level, avoided has to be disadvantage of the necessary complete draining of the motor oil and refilling of the entire system is necessary after installation of the connecting line and particular attention has to be paid to complete ventilation of the measuring system and proposed is therefore a connecting line having an adapter arrangement on the side of the internal combustion engine, such as the measuring arrangement disclosed in AT 4 139 U2, which can be inserted through an existing opening on the engine from the top into the crankcase sump and whereby its upwardly oriented intake area is essentially designed in the he way of a siphon. Adapting the connecting line leading to the communicating measuring vessel is thereby greatly simplified.
Nevertheless, situations or operational conditions of the engine may occur during the detection of the consumption of operational fluids or between measurements for the determination of consumption of specific operational fluids, such as lubricating oil in internal combustion engines, which change the condition of the operational fluid in such a manner that sensible quantity measurement or consumption measurements are no longer possible. For example, the consumption values can be falsified through the import of foreign substances into the operational fluid to be measured, for instance imported motor fuel or carbon particles into the lubricating oil, or through extreme foaming or chemical/physical changes in the operational fluid as a result of a lengthy continuous influence of high operational temperatures.
Any consumption measurement of an operational fuel is only informative and meaningful if the usability potential of the specific operational fluid is observed. This usability potential is determined through the quantity of operational fluid that is available for the engine, on the one hand, and its condition, on the other hand. As parameters for the characterization of the supply quantity is considered the existing or consumed mass, volume, fluid level, etc., while parameters for the evaluation of the condition can be temperature, density, viscosity, acoustic velocity, compressibility, specific electric conductivity, dielectric constants, magnetic permeability or susceptibility (ferromagnetic, paramagnetic or diamagnetic), opacity, and optical spectrum, etc. For example, import of motor fuel into the lubricating oil changes its density and viscosity, as it is also the case with extreme foaming. DE 101 49 852 A1 describes a method to calculate the decrease in quality of motor oil, which does not determine this decrease in quality from a measurement of the above-mentioned parameters but the decrease is derived from the actually measured change of the oil quantity. Linking of the quantity parameter and the condition parameter is thereby not possible. In contrast, EP 1 286 161 A2 discloses device merely for the detection of the quality of motor oil without considering a combination with the quantity parameter, which determines the oil temperature as well as at least one quality parameter by means of a multifunctional sensor. The parameter of the oil consumption in terms of quantity or the existing oil quantity is not considered.
Both parameters determining the usability potential of the operational fluid, namely the quantity as well as the condition, are independent in principal and one parameter can be kept respectively constant depending on the testing object and the other parameter can be observed—or the change of both parameters is monitored during the course of the test. For example, tested can be the quantity of consumption at a nearly constant condition—or tested can be degradation of the condition of the operational fluid at nearly constant quantity in supply.
Such information would be of high significance in the increasingly automated measuring and testing operation and it is the first object of the present invention to provide systems and methods of the aforementioned type to make possible a testing apparatus relative to the measurement-related determination of parameters of operational fluids and to give information in a systematic and simple manner about the permissibility or possible validity of the specific parameters of the operational fluids and possibly about other measuring and testing results. An additional object is to realize with such systems and methods the accuracy of gravimetric quantity determination or quantity determination at intervals known from prior art in another connection, which can also be attached and operated while the engine is running and make additionally possible the evaluation of the usability potential and give thereby information about the utility of the measured values or of the entire testing process.